A 3-day training program would be imparted to familiarize them of the research protocol, the field operations for the activities of the census/survey and the research trial and measures for completing the forms. A series of data collection forms would be drafted (initially in English; then translated to Urdu and Sindhi languages) to collect information during the entire research period. A case recruitment form (CRF) would be drafted, which would be filled by research medical officers and would bear questions/items on birth history, immunization status, medical history, anthropometry and physical examination. The subjects would be followed up on a regular basis (2 times a week) by the research appointed community health workers with a minimum qualification of matriculation (grade 10 education), using a pre-defined follow up form. The CHWs will record data on immunization status, medical history and management of any ailment (especially diarrhea), anthropometric assessment and medical examination, and laboratory test results (blood serology and ELISA). Immunization status of each recruit would be maintained for every OPV dose provided to the recruited infants. The data would be collected by the CHWs during their regular follow ups in the area through assessment of vaccination records and finger marking during or after campaigns. A supplementation form would be maintained regularly to ensure compliance in all groups and replenished. This would be recorded by the community health workers undertaking household surveillance. All the forms would bear the general information of the child and the intervention codes allotted by Atco laboratories. Research medical officers, in addition to leading the field teams, would also be entrusted to oversee any untoward events/reactions, among the study subjects. These would be brought to their notice by the circulating CHWs. If encountered, the adverse events would be documented followed by its clinically appropriate treatment. If a child, outside the recruited cohort is identified as in need of health care, the CHWs may refer the child to the Taluka Hospital, Hala.